Telecommunications apparatus and methods

ABSTRACT

A method of operating a terminal device and network infrastructure equipment in a wireless telecommunications system for communicating on a primary cell supporting a primary component carrier on radio resources within a first frequency band and a secondary cell supporting a secondary component carrier on radio resources within a second frequency band. The infrastructure equipment establishes plural configuration settings for the secondary carrier based on measurements of radio usage in the second frequency band, which are conveyed to the terminal device. The terminal device makes channel quality measurements for the secondary component carrier according to the different configuration settings and reports these to the infrastructure equipment. Based on the measurements of channel quality for the different configurations, the infrastructure equipment selects one of the configuration settings, and conveys an indication of this to the terminal device in association with an allocation of transmission resources on the secondary component carrier.

BACKGROUND Field

The present disclosure relates to mobile communications networks andmethods for communicating data using mobile communications networks,infrastructure equipment for mobile communications networks,communications devices for communicating data via mobile communicationsnetworks and methods of communicating via mobile communicationsnetworks.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

It is well known in the field of wireless telecommunications for regionsof the radio spectrum to be assigned to different mobile networkoperators (MNO) for their exclusive use through a license. A licensetypically grants an MNO exclusive use over a number of years of apredefined portion of the radio frequency spectrum in which to deploy amobile communications network (e.g. GSM, WCDMA/HSPA, LTE/LTE-A). As aresult of this approach, an operator has guarantees of no other radioservices interfering with the radio resources that have been assigned tothe operator, and within the limitations of the license conditions ithas exclusive control over what radio technology it deploys in thenetwork. Consequently, a wireless telecommunications system that isprimarily designed to operate using radio resources that have beenlicensed for exclusive use by the wireless telecommunications system canoperate with a degree of centralised control and coordination to helpmake most efficient use of the available radio resources. Such awireless telecommunication system also manages all the interferenceinternally, based on standard specifications, since the licence grantsit good immunity from external interference sources. Coexistence ofdifferent devices deployed on an MNO's licensed band is managed throughconformance to relevant radio standards. Licensed spectrum is todayusually assigned to operators via government-organised auctions, butso-called “beauty contests” continue also to be in use.

It is also well known in the field of wireless telecommunications forregions of the available radio spectrum to remain unlicensed. Unlicensed(licence exempt) radio spectrum may, at least to some extent, be freelyused by a number of different technologies, such as Wi-Fi and Bluetoothand other non-3GPP radio access technologies. Operating parameters fordevices using unlicensed spectrum bands are typically stipulated bytechnical regulatory requirements such as e.g. the FCC Part 15 rule for2.4 GHz ISM band. Coexistence of different devices deployed onunlicensed band, due to the lack of centralised coordination andcontrol, is usually based on such technical rules and various politenessprotocols.

The use of wireless telecommunications system technologies designed foroperation on licensed radio spectrum, such as LTE, is becoming more andmore prevalent, both in terms of increasing take-up of established usesfor wireless telecommunications technologies, and also the introductionof new uses, e.g., in the developing field of machine-typecommunications (MTC). In order to help provide more bandwidth to supportthis increased use of wireless telecommunications technologies, it hasrecently been proposed to use unlicensed radio spectrum resources tosupport operations on licensed radio spectrum.

However, in contrast to licensed spectrum, unlicensed spectrum can beshared and used among different technologies, or different networksusing the same technology, without any co-ordinated/centralised control,for example to provide protection against interference. As a consequenceof this, the use of wireless technologies in unlicensed spectrum can besubject to unpredictable interference and has no guarantees of spectrumresources, i.e. the radio connection takes place on a best effort basis.This means that wireless network technologies, such as LTE, which aregenerally designed to operate using licensed radio resources, requiremodified approaches to allow them to efficiently use unlicensed radioresources, and in particular to co-exist reliably and fairly with otherradio access technologies that may be simultaneously operating in theunlicensed spectrum band.

Therefore, deploying a mobile radio access technology system primarilydesigned to operate in licensed spectrum bands (i.e. having exclusiveaccess to, and hence a level of control over, the relevant radioresources) in a manner which is required by operation in unlicensedspectrum bands (i.e. without having exclusive access to at least some ofthe relevant radio resources), gives rise to new technical challenges.

SUMMARY

According to an aspect of the disclosure there is provided a method ofoperating a terminal device in a wireless telecommunications system forcommunicating with network infrastructure equipment on a primary cellsupporting a primary component carrier on radio resources within a firstfrequency band and a secondary cell supporting a secondary componentcarrier on radio resources within a second frequency band, wherein themethod comprises: receiving from the network infrastructure equipment anindication of a plurality of potential configuration settings for thesecondary component carrier; receiving from the network infrastructureequipment an allocation message indicating an allocation of transmissionresources to be used for communicating data between the networkinfrastructure equipment and the terminal device on the secondarycomponent carrier; receiving from the network infrastructure equipmentin association with the allocation message an indication of a selectedone of the plurality of potential configuration settings for thesecondary component carrier to be used for communicating the data; andreceiving the data from the network infrastructure equipment using theallocated resources on the secondary component carrier operating inaccordance with the selected one of the plurality of potentialconfiguration settings.

According to another aspect of the disclosure there is provided aterminal device for use in a wireless telecommunications system forcommunicating with network infrastructure equipment on a primary cellsupporting a primary component carrier on radio resources within a firstfrequency band and a secondary cell supporting a secondary componentcarrier on radio resources within a second frequency band, wherein theterminal device comprises a controller unit and a transceiver unitconfigured to operate together to: receive from the networkinfrastructure equipment an indication of a plurality of potentialconfiguration settings for the secondary component carrier; receive fromthe network infrastructure equipment an allocation message indicating anallocation of transmission resources to be used for communicating databetween the network infrastructure equipment and the terminal device onthe secondary component carrier; receive from the network infrastructureequipment in association with the allocation message an indication of aselected one of the plurality of potential configuration settings forthe secondary component carrier to be used for communicating the data;and receive the data from the network infrastructure equipment using theallocated resources on the secondary component carrier operating inaccordance with the selected one of the plurality of potentialconfiguration settings.

According to another aspect of the disclosure there is providedcircuitry for a terminal device for use in a wireless telecommunicationssystem for communicating with network infrastructure equipment on aprimary cell supporting a primary component carrier on radio resourceswithin a first frequency band and a secondary cell supporting asecondary component carrier on radio resources within a second frequencyband, wherein the circuitry comprises a controller element and atransceiver element configured to operate together to: receive from thenetwork infrastructure equipment an indication of a plurality ofpotential configuration settings for the secondary component carrier;receive from the network infrastructure equipment an allocation messageindicating an allocation of transmission resources to be used forcommunicating data between the network infrastructure equipment and theterminal device on the secondary component carrier; receive from thenetwork infrastructure equipment in association with the allocationmessage an indication of a selected one of the plurality of potentialconfiguration settings for the secondary component carrier to be usedfor communicating the data; and receive the data from the networkinfrastructure equipment using the allocated resources on the secondarycomponent carrier operating in accordance with the selected one of theplurality of potential configuration settings.

According to another aspect of the disclosure there is provided a methodof operating network infrastructure equipment in a wirelesstelecommunications system for communicating with a terminal device on aprimary cell supporting a primary component carrier on radio resourceswithin a first frequency band and a secondary cell supporting asecondary component carrier on radio resources within a second frequencyband, wherein the method comprises: transmitting to the terminal devicean indication of a plurality of potential configuration settings for thesecondary component carrier; transmitting to the terminal device anallocation message indicating an allocation of transmission resources tobe used by for communicating data to the terminal device on thesecondary component carrier; transmitting to the terminal device inassociation with the allocation message an indication of a selected oneof the plurality of potential configuration settings for the secondarycomponent carrier to be used for communicating the data; andtransmitting the data to the terminal device using the allocatedresources on the secondary component carrier operating in accordancewith the selected one of the plurality of potential configurationsettings.

According to another aspect of the disclosure there is provided networkinfrastructure equipment for use in a wireless telecommunications systemfor communicating with a terminal device on a primary cell supporting aprimary component carrier on radio resources within a first frequencyband and a secondary cell supporting a secondary component carrier onradio resources within a second frequency band, wherein the networkinfrastructure equipment comprises a controller unit and a transceiverunit configured to operate together to: transmit to the terminal devicean indication of a plurality of potential configuration settings for thesecondary component carrier; transmit to the terminal device anallocation message indicating an allocation of transmission resources tobe used by for communicating data to the terminal device on thesecondary component carrier; transmit to the terminal device inassociation with the allocation message an indication of a selected oneof the plurality of potential configuration settings for the secondarycomponent carrier to be used for communicating the data; and transmitthe data to the terminal device using the allocated resources on thesecondary component carrier operating in accordance with the selectedone of the plurality of potential configuration settings.

According to another aspect of the disclosure there is providedcircuitry for network infrastructure equipment for use in a wirelesstelecommunications system for communicating with a terminal device on aprimary cell supporting a primary component carrier on radio resourceswithin a first frequency band and a secondary cell supporting asecondary component carrier on radio resources within a second frequencyband, wherein the circuitry comprises a controller element and atransceiver element configured to operate together to: transmit to theterminal device an indication of a plurality of potential configurationsettings for the secondary component carrier; transmit to the terminaldevice an allocation message indicating an allocation of transmissionresources to be used by for communicating data to the terminal device onthe secondary component carrier; transmit to the terminal device inassociation with the allocation message an indication of a selected oneof the plurality of potential configuration settings for the secondarycomponent carrier to be used for communicating the data; and transmitthe data to the terminal device using the allocated resources on thesecondary component carrier operating in accordance with the selectedone of the plurality of potential configuration settings.

Further respective aspects and features are defined by the appendedclaims.

The foregoing paragraphs have been provided by way of generalintroduction, and are not intended to limit the scope of the followingclaims. The described embodiments, together with further advantages,will be best understood by reference to the following detaileddescription taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 provides a schematic diagram illustrating an example of a mobiletelecommunication system;

FIG. 2 provides a schematic diagram illustrating a LTE radio frame;

FIG. 3 provides a schematic diagram illustrating an example of a LTEdownlink radio subframe;

FIG. 4 schematically represents a wireless telecommunications systemaccording to an embodiment of the disclosure; and

FIG. 5 is a signalling ladder diagrams representing communicationsbetween a base station and a terminal device operating in accordancewith some embodiments of the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 provides a schematic diagram illustrating some basicfunctionality of a mobile telecommunications network/system 100operating in accordance with LTE principles and which may be adapted toimplement embodiments of the disclosure as described further below.Various elements of FIG. 1 and their respective modes of operation arewell-known and defined in the relevant standards administered by the3GPP (RTM) body, and also described in many books on the subject, forexample, Holma H. and Toskala A [1]. It will be appreciated thatoperational aspects of the telecommunications network which are notspecifically described below may be implemented in accordance with anyknown techniques, for example according to the relevant standards.

The network 100 includes a plurality of base stations 101 connected to acore network 102. Each base station provides a coverage area 103 (i.e. acell) within which data can be communicated to and from terminal devices104. Data is transmitted from base stations 101 to terminal devices 104within their respective coverage areas 103 via a radio downlink. Data istransmitted from terminal devices 104 to the base stations 101 via aradio uplink. The uplink and downlink communications are made usingradio resources that are licenced for use by the operator of the network100. The core network 102 routes data to and from the terminal devices104 via the respective base stations 101 and provides functions such asauthentication, mobility management, charging and so on. Terminaldevices may also be referred to as mobile stations, user equipment (UE),user terminal, mobile radio, and so forth. Base stations may also bereferred to as transceiver stations/nodeBs/e-nodeBs, and so forth.

Mobile telecommunications systems such as those arranged in accordancewith the 3GPP defined Long Term Evolution (LTE) architecture use anorthogonal frequency division modulation (OFDM) based interface for theradio downlink (so-called OFDMA) and a single carrier frequency divisionmultiple access scheme (SC-FDMA) on the radio uplink. FIG. 2 shows aschematic diagram illustrating an OFDM based LTE downlink radio frame201. The LTE downlink radio frame is transmitted from a LTE base station(known as an enhanced Node B) and lasts 10 ms. The downlink radio framecomprises ten subframes, each subframe lasting 1 ms. A primarysynchronisation signal (PSS) and a secondary synchronisation signal(SSS) are transmitted in the first and sixth subframes of the LTE frame.A physical broadcast channel (PBCH) is transmitted in the first subframeof the LTE frame.

FIG. 3 is a schematic diagram of a grid which illustrates the structureof an example conventional downlink LTE subframe. The subframe comprisesa predetermined number of symbols which are transmitted over a 1 msperiod. Each symbol comprises a predetermined number of orthogonalsubcarriers distributed across the bandwidth of the downlink radiocarrier.

The example subframe shown in FIG. 3 comprises 14 symbols and 1200subcarriers spread across a 20 MHz bandwidth licenced for use by theoperator of the network 100, and this example is the first subframe in aframe (hence it contains PBCH). The smallest allocation of physicalresource for transmission in LTE is a resource block comprising twelvesubcarriers transmitted over one subframe. For clarity, in FIG. 3, eachindividual resource element is not shown, instead each individual box inthe subframe grid corresponds to twelve subcarriers transmitted on onesymbol.

FIG. 3 shows in hatching resource allocations for four LTE terminals340, 341, 342, 343. For example, the resource allocation 342 for a firstLTE terminal (UE 1) extends over five blocks of twelve subcarriers (i.e.60 subcarriers), the resource allocation 343 for a second LTE terminal(UE2) extends over six blocks of twelve subcarriers (i.e. 72subcarriers), and so on.

Control channel data can be transmitted in a control region 300(indicated by dotted-shading in FIG. 3) of the subframe comprising thefirst “n” symbols of the subframe where “n” can vary between one andthree symbols for channel bandwidths of 3 MHz or greater and where “n”can vary between two and four symbols for a channel bandwidth of 1.4MHz. For the sake of providing a concrete example, the followingdescription relates to host carriers with a channel bandwidth of 3 MHzor greater so the maximum value of “n” will be 3 (as in the example ofFIG. 3). The data transmitted in the control region 300 includes datatransmitted on the physical downlink control channel (PDCCH), thephysical control format indicator channel (PCFICH) and the physical HARQindicator channel (PHICH). These channels transmit physical layercontrol information. Control channel data can also or alternatively betransmitted in a second region of the subframe comprising a number ofsubcarriers for a time substantially equivalent to the duration of thesubframe, or substantially equivalent to the duration of the subframeremaining after the “n” symbols. The data transmitted in this secondregion is transmitted on the enhanced physical downlink control channel(EPDCCH). This channel transmits physical layer control informationwhich may be in addition to that transmitted on other physical layercontrol channels.

PDCCH and EPDCCH contain control data indicating which subcarriers ofthe subframe have been allocated to specific terminals (or all terminalsor subset of terminals). This may be referred to as physical-layercontrol signalling/data. Thus, the PDCCH and/or EPDCCH data transmittedin the control region 300 of the subframe shown in FIG. 3 would indicatethat UE1 has been allocated the block of resources identified byreference numeral 342, that UE2 has been allocated the block ofresources identified by reference numeral 343, and so on.

PCFICH contains control data indicating the size of the control region(i.e. between one and three symbols for channel bandwidths of 3 MHz orgreater and between two and four symbols for channel bandwidths of 1.4MHz).

PHICH contains HARQ (Hybrid Automatic Request) data indicating whetheror not previously transmitted uplink data has been successfully receivedby the network.

Symbols in a central band 310 of the time-frequency resource grid areused for the transmission of information including the primarysynchronisation signal (PSS), the secondary synchronisation signal (SSS)and the physical broadcast channel (PBCH). This central band 310 istypically 72 subcarriers wide (corresponding to a transmission bandwidthof 1.08 MHz). The PSS and SSS are synchronisation signals that oncedetected allow a LTE terminal device to achieve frame synchronisationand determine the physical layer cell identity of the enhanced Node Btransmitting the downlink signal. The PBCH carries information about thecell, comprising a master information block (MIB) that includesparameters that LTE terminals use to properly access the cell. Datatransmitted to terminals on the physical downlink shared channel(PDSCH), which may also be referred to as a downlink data channel, canbe transmitted in other resource elements of the subframe. In generalPDSCH conveys a combination of user-plane data and non-physical layercontrol-plane data (such as Radio Resource Control (RRC) and Non AccessStratum (NAS) signalling). The user-plane data and non-physical layercontrol-plane data conveyed on PDSCH may be referred to as higher layerdata (i.e. data associated with a layer higher than the physical layer).

FIG. 3 also shows a region of PDSCH containing system information andextending over a bandwidth of R344. A conventional LTE subframe willalso include reference signals which are not shown in FIG. 3 in theinterests of clarity.

The number of subcarriers in a LTE channel can vary depending on theconfiguration of the transmission network. Typically this variation isfrom 72 sub carriers contained within a 1.4 MHz channel bandwidth to1200 subcarriers contained within a 20 MHz channel bandwidth (asschematically shown in FIG. 3). As is known in the art, data transmittedon the PDCCH, PCFICH and PHICH is typically distributed on thesubcarriers across the entire bandwidth of the subframe to provide forfrequency diversity.

The communications between the base stations 101 and the terminaldevices 104 are conventionally made using radio resources that have beenlicensed for exclusive use by the operator of the network 100. Theselicensed radio resources will be only a portion of the overall radiospectrum. Other devices within the environment of the network 100 may bewirelessly communicating using other radio resources. For example, adifferent operator's network may be operating within the samegeographical region using different radio resources that have beenlicensed for use by the different operator. Other devices may beoperating using other radio resources in an unlicensed radio spectrumband, for example using Wi-Fi or Bluetooth technologies.

As noted above, it has been proposed that a wireless telecommunicationsnetwork using radio resources in a licensed portion of the radiospectrum might be supported by using radio resources in an unlicensedportion of the radio spectrum (i.e. a portion of the radio spectrum overwhich the wireless telecommunications network does not have exclusiveaccess, but rather which is shared by other access technologies and/orother wireless telecommunications networks). In particular, it has beenproposed that carrier aggregation based techniques may be used to allowunlicensed radio resources to be used in conjunction with licensed radioresources.

In essence, carrier aggregation allows for communications between a basestation and a terminal device to be made using more than one carrier.This can increase the maximum data rate that may be achieved between abase station and a terminal device as compared to when using only onecarrier and can help enable more efficient and productive use offragmented spectrum. Individual carriers that are aggregated arecommonly referred to as component carriers (or sometimes simplycomponents). In the context of LTE, carrier aggregation was introducedin Release 10 of the standard. In accordance with the current standardsfor carrier aggregation in an LTE-based system, up to five componentcarriers can be aggregated for each of downlink and uplink. Thecomponent carriers are not required to be contiguous with one anotherand can have a system bandwidth corresponding to any of the LTE-definedvalues (1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz), therebyallowing a total bandwidth of up to 100 MHz. Of course it will beappreciated this is just one example of a specific carrier aggregationimplementation and other implementations may allow for different numbersof component carriers and/or bandwidths.

Further information on the operation of carrier aggregation in thecontext of LTE-based wireless telecommunications systems can be found inthe relevant standards documents, such as ETSI TS 136 211 V11.5.0(2014-01)/3GPP TS 36.211 version 11.5.0 Release 11 [2], ETSI TS 136 212V11.4.0 (2014-01)/3GPP TS 36.212 version 11.4.0 Release 11 [3]; ETSI TS136 213 V11.6.0 (2014-03)/3GPP TS 36.213 version 11.6.0 Release 11 [4];ETSI TS 136 321 V11.5.0 (2014-03)/3GPP TS 36.321 version 11.5.0 Release11 [5]; and ETSI TS 136 331 V11.7.0 (2014-03)/3GPP TS 36.331 version11.7.0 Release 11 [6].

In accordance with the terminology and implementation used for carrieraggregation in the context of an LTE-based system, a cell is denoted the‘primary cell’, or Pcell, for a terminal device if it is the cell thatis initially configured during connection setup for the terminal device.Thus the primary cell handles RRC (radio resource control) connectionestablishment/re-establishment for the terminal device. The primary cellis associated with a downlink component carrier and an uplink componentcarrier (CoC). These may sometimes be referred to herein as primarycomponent carriers. A cell that is configured for use by the terminaldevice after initial connection establishment on the Pcell is termed a‘secondary cell’, or Scell. Thus the secondary cells are configuredafter connections establishment to provide additional radio resources.The carriers associated with Scells may sometimes be referred to hereinas secondary component carriers. Since in LTE up to five componentcarriers can be aggregated, up to four Scells (correspondinglyassociated with up to four secondary component carriers) can beconfigured for aggregation with the primary cell (associated with theprimary component carrier). An Scell might not have both a downlink anduplink component carrier and the association between uplink componentcarriers and downlink component carriers is signalled in SIB2 on eachdownlink component carrier. The primary cell supports PDCCH and PDSCH ondownlink and PUSCH and PUCCH on uplink whereas the secondary cell(s)support PDCCH and PDSCH on downlink and PUSCH on uplink, but not PUCCH.Measurement and mobility procedures are handled on the Pcell and thePcell cannot be de-activated. The Scell(s) may be dynamically activatedand deactivated, for example according to traffic needs, though MAClayer signalling to the terminal device. An Scells for a terminal devicemay also be deactivated automatically (time out) if the terminal devicedoes not receive any transmission resource allocations on the Scell fora threshold amount of time.

Some aspects of physical layer control signalling for an LTE-basedimplementation of carrier aggregation based on the current standards arenow described.

Each downlink component carrier has the normal LTE control channels:(E)PDCCH, PCFICH and PHICH. However, carrier aggregation introduces thepossibility of so-called cross-carrier scheduling (XCS) on PDCCH. Tosupport cross-carrier scheduling, a downlink control information (DCI)message on PDCCH includes a carrier indicator field (CIF) comprisingthree bits to indicate which of the component carriers the PDCCH messageapplies to. If there is no CIF, the PDCCH is treated as applying to thecarrier on which it is received. A motivation for providingcross-carrier scheduling primarily applies for heterogeneous network(het-net) scenarios where overlaid macro- and small-cells may operatecarrier aggregation in the same band. The effects of interferencebetween the respective macro- and small-cells' PDCCH signalling can bemitigated by having the macro-cell transmit its PDCCH signalling on onecomponent carrier at relatively high transmit power (to provide coverageacross the macro-cell), while the small-cells use an alternativecomponent carrier for their PDCCH scheduling.

The control region supporting PDCCH may differ in size (i.e. number ofOFDM symbols) between component carriers, so they can carry differentPCFICH values. However, the potential for interference in the controlregion in a het-net implementation may mean that PCFICH cannot bedecoded on a particular component carrier. Therefore, current LTEstandards allow for each component to carrier a semi-static indicationof which OFDM symbol PDSCH can be assumed to begin in each subframe. Iffewer OFDM symbols are actually used for the control region, thefree/spare OFDM symbol(s) may be used for PDSCH transmissions toterminal devices which are not being cross-carrier scheduled as theywill decode the actual PCFICH. If more OFDM symbols actually used forthe control region, there will be some degree of performance degradationfor the cross-carrier scheduled terminal devices.

PHICH signalling is sent on the downlink component carrier that sent thePDCCH signalling containing the PUSCH allocation to which the PHICHsignalling relates. Accordingly, one downlink component carrier maycarry PHICH for more than one component carrier.

In the uplink, the basic operation of PUCCH is not altered by theintroduction of carrier aggregation. However, a new PUCCH format (format3) is introduced to support the sending of acknowledgement signalling(ACK/NACK signalling) for multiple downlink component carriers, and withsome alterations to format 1b to increase the number of ACK/NACK bits itcan carry.

In current LTE-based carrier aggregation scenarios, primary andsecondary synchronisation signalling (PSS and SSS) are transmitted onall component carriers using the same physical-layer cell identity (PCI)and component carriers are all synchronised with one another. This canhelp with cell search and discovery procedures. Issues relating tosecurity and system information (SI) are handled by the Pcell. Inparticular, when activating an Scell, the Pcell delivers the relevant SIfor the Scell to the terminal device using dedicated RRC signalling. Ifthe system information relating to a Scell changes, the Scell isreleased and re-added by Pcell RRC signalling (in one RRC message).Pcell changes, e.g. due to long-term fluctuations in channel qualityacross the Pcell bandwidth, are handled using a modified handoverprocedure. The source Pcell passes all the relevant carrier aggregation(CA) information to the target Pcell so the terminal device can begin touse all the assigned component carriers when handover is complete.

Random access procedures are primarily handled on the uplink componentcarrier of Pcell for a terminal device, although some aspects ofcontention resolution signalling may be cross-carrier scheduled toanother serving cell (i.e. an Scell).

As noted above, carrier aggregation is one approach for making use ofunlicensed radio spectrum resources in wireless communication networkswhich are primarily designed to use licensed radio spectrum. In broadsummary, a carrier aggregation based approach may be used to configureand operate a first component carrier (e.g. a primary component carrierassociated with a Pcell in LTE terminology) within a region of the radiospectrum that has been licensed for use by a wireless telecommunicationsnetwork, and to also configure and operate one or more further componentcarriers (e.g. a secondary component carrier associated with an Scell inLTE terminology) in an unlicensed region of the radio spectrum. Thesecondary component carrier(s) operating in the unlicensed region of theradio spectrum may do so in an opportunistic manner by making use of theunlicensed radio resources when they are available. There may also beprovisions made for restricting the extent to which a given operator canmake use of the unlicensed radio resources, for example by defining whatmight be referred to as politeness protocols.

Although known carrier aggregation schemes can form a basis for usingunlicensed radio spectrum resources (or other forms of shared radioresources) in conjunction with licensed radio spectrum resources, somemodifications to known carrier aggregation techniques may be appropriateto help optimise performance. This is because radio interference in theunlicensed radio spectrum can be expected to be subject to a wider rangeof unknown and unpredictable variations in time and frequency than mightbe seen within a region of the radio spectrum which has been licensedfor use by a particular wireless applications system. For a givenwireless telecommunications system operating in accordance with a giventechnology, such as LTE-A, interference in the unlicensed radio spectrummay arise from other systems operating quantity same technology, orsystems operating according to different technologies, such as Wi-Fi orBluetooth.

FIG. 4 schematically shows a telecommunications system 400 according toan embodiment of the disclosure. The telecommunications system 400 inthis example is based broadly on a LTE-type architecture. As such manyaspects of the operation of the telecommunications system 400 arestandard and well understood and not described here in detail in theinterest of brevity. Operational aspects of the telecommunicationssystem 400 which are not specifically described herein may beimplemented in accordance with any known techniques, for exampleaccording to the established LTE-standards and known variations thereof.

The telecommunications system 400 comprises a core network part (evolvedpacket core) 402 coupled to a radio network part. The radio network partcomprises a base station (evolved-nodeB) 404, a first terminal device406 and a second terminal device 408. It will of course be appreciatedthat in practice the radio network part may comprise a plurality of basestations serving a larger number of terminal devices across variouscommunication cells. However, only a single base station and twoterminal devices are shown in FIG. 4 in the interests of simplicity.

Although not part of the telecommunications system 400 itself, alsoshown in FIG. 4 are some other devices which are operable to wirelesslycommunicate with one another and which are operating within the radioenvironment of the telecommunications system 400. In particular, thereis a pair of wireless access devices 416 communicating with one anothervia radio link 418 operating in accordance with a Wi-Fi standard and apair of Bluetooth devices 420 communicating with one another via radiolink 422 operating in accordance with a Bluetooth standard. These otherdevices represent a potential source of radio interference for thetelecommunications system 400. It will be appreciated that in practicethere will typically be many more such devices operating in the radioenvironment of the wireless telecommunications system 400, and only twopairs of devices 416, 418 are shown in FIG. 4 for simplicity.

As with a conventional mobile radio network, the terminal devices 406,408 are arranged to wirelessly communicate data to and from the basestation (transceiver station) 404. The base station is in turncommunicatively connected to a serving gateway, S-GW, (not shown) in thecore network part which is arranged to perform routing and management ofmobile communications services to the terminal devices in thetelecommunications system 400 via the base station 404. In order tomaintain mobility management and connectivity, the core network part 402also includes a mobility management entity (not shown) which manages theenhanced packet service, EPS, connections with the terminal devices 406,408 operating in the communications system based on subscriberinformation stored in a home subscriber server, HSS. Other networkcomponents in the core network (also not shown for simplicity) include apolicy charging and resource function, PCRF, and a packet data networkgateway, PDN-GW, which provides a connection from the core network part402 to an external packet data network, for example the Internet. Asnoted above, the operation of the various elements of the communicationssystem 400 shown in FIG. 4 may be broadly conventional apart from wheremodified to provide functionality in accordance with embodiments of thedisclosure as discussed herein.

The terminal devices 406, 408 each comprise a transceiver unit 406 a,408 a for transmission and reception of wireless signals and acontroller unit 406 b, 408 b configured to control the operation of therespective devices 406, 408 in accordance with embodiments of thedisclosure. The respective controller units 406 b, 408 b may eachcomprise a processor unit which is suitably configured/programmed toprovide the desired functionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. For each of the terminal devices 406, 408,their respective transceiver units 406 a, 408 a and controller units 406b, 408 b are schematically shown in FIG. 4 as separate elements for easeof representation. However, it will be appreciated that for eachterminal device the functionality of these units can be provided invarious different ways, for example using a single suitably programmedgeneral purpose computer, or suitably configured application-specificintegrated circuit(s)/circuitry, or using a plurality of discretecircuitry/processing elements for providing different elements of thedesired functionality. It will be appreciated the terminal devices 406,408 will in general comprise various other elements associated withtheir operating functionality in accordance with established wirelesstelecommunications techniques (e.g. a power source, possibly a userinterface, and so forth).

As has become commonplace in the field of wireless telecommunications,terminal devices may support Wi-Fi and Bluetooth functionality inaddition to cellular/mobile telecommunications functionality. Thus thetransceiver units 406 a, 408 a of the respective terminal devices maycomprise functional modules operable according to different wirelesscommunications operating standards. For example, the terminal devices'transceiver units may each comprise an LTE transceiver module forsupporting wireless communications in accordance with an LTE-basedoperating standard, a WLAN transceiver module for supporting wirelesscommunications in accordance with a WLAN operating standard (e.g. aWi-Fi standard), and a Bluetooth transceiver module for supportingwireless communications in accordance with a Bluetooth operatingstandard. The underlying functionality of the different transceivermodules may be provided in accordance with conventional techniques. Forexample, a terminal device may have separate hardware elements toprovide the functionality of each transceiver module, or alternatively,a terminal device might comprise at least some hardware elements whichare configurable to provide some or all functionality of multipletransceiver modules. Thus the transceiver units 406 a, 408 a of theterminal devices 406, 408 represented in FIG. 4 are assumed here toprovide the functionality of an LTE transceiver module, a Wi-Fitransceiver module and a Bluetooth transceiver module in accordance withconventional wireless communications techniques.

The base station 404 comprises a transceiver unit 404 a for transmissionand reception of wireless signals and a controller unit 404 b configuredto control the base station 404. The controller unit 404 b may comprisea processor unit which is suitably configured/programmed to provide thedesired functionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. The transceiver unit 404 a and thecontroller unit 404 b are schematically shown in FIG. 4 as separateelements for ease of representation. However, it will be appreciatedthat the functionality of these units can be provided in variousdifferent ways, for example using a single suitably programmed generalpurpose computer, or suitably configured application-specific integratedcircuit(s)/circuitry or using a plurality of discretecircuitry/processing elements for providing different elements of thedesired functionality. It will be appreciated the base station 404 willin general comprise various other elements associated with its operatingfunctionality. For example, the base station 404 will in generalcomprise a scheduling entity responsible for scheduling communications.The functionality of the scheduling entity may, for example, be subsumedby the controller unit 404 b.

Thus, the base station 404 is configured to communicate data with thefirst and second terminal devices 406, 408 over respective first andsecond radio communication links 410, 412. The wirelesstelecommunications system 400 supports a carrier aggregation mode ofoperation in which the first and second radio communication links 410,412 each comprise a wireless access interface provided by multiplecomponent carriers. For example, each radio communication link maycomprise a primary component carrier and one or more secondary componentcarriers. Furthermore, the elements comprising the wirelesstelecommunications system 400 in accordance with this embodiment of thedisclosure are assumed to support carrier aggregation in an unlicensedspectrum mode. In this unlicensed spectrum mode the base stationcommunicates with terminal devices using a primary component carrieroperating on radio resources within a first frequency band that has beenlicensed for use by the wireless telecommunications system and one ormore secondary component carriers operating on radio resources within asecond frequency band that has not been licensed for exclusive use bythe wireless telecommunications system. The first frequency band maysometimes be referred to herein as a licensed frequency band and thesecond frequency band may sometimes be referred to herein as anunlicensed (U) frequency band. In the context of an LTE-based wirelesstelecommunications system, such as that represented in FIG. 4, operationin the unlicensed frequency band may be referred to as an LTE-U mode ofoperation. The first (licenced) frequency band may be referred to as anLTE band (or more particularly an LTE-A band) and the second(unlicensed) frequency band may be referred to as an LTE-U band.Resources on the LTE-U band may be referred to as U-resources. Aterminal device able to make use of U-resources may be referred to as aU-terminal device (or U-UE). More generally, the qualifier “U” may beused herein to conveniently identify operations in respect of theunlicensed frequency band.

It will be appreciated that the use of carrier aggregation techniquesand the use of unlicensed spectrum resources (i.e. resources that may beused by other devices without centralised coordination) in accordancewith embodiments of the disclosure may be based generally on previouslyproposed principles for such modes of operation, for example asdiscussed above, but with modifications as described herein to provideadditional functionality in accordance with embodiments of the presentdisclosure. Accordingly, aspects of the carrier aggregation andunlicensed spectrum operation which are not described in detail hereinmay be implemented in accordance with known techniques.

Modes of operation for the wireless telecommunications network 400represented in FIG. 4 in accordance with certain embodiments of thedisclosure will now be described. The general scenario for theseembodiments is assumed to be one in which a carrier aggregation capableterminal device is operating in an LTE-A cell as normal, and the basestation determines that it should configure the LTE-U capable terminaldevice with an additional aggregated carrier using LTE-U resources. Thespecific reason why the base station determines that it should configurea particular terminal device for LTE-U based carrier aggregation is notsignificant. Thus the LTE-A carrier provides a Pcell for the terminaldevice and the LTE-U resources provide one or more Scell(s) for theterminal device. It will be appreciated the LTE-A resources may also beused to provide component carriers associated with one or more furtherScells(s) in accordance with conventional carrier aggregationtechniques. For the examples described with reference to FIG. 4, theLTE-A transmissions in the licenced frequency band and the LTE-Utransmissions in the unlicensed frequency band, and thus the Pcell andScell(s), are both made from the same base station 404, but this may notbe the case in other example embodiments. The LTE-U carrier could ingeneral be utilised with a TDD (time division duplex) or FDD (frequencydivision duplex) frame structure. However, a consequence of some aspectsof existing regulatory restrictions on unlicensed spectrum usage in someregions means that TDD or downlink-only FDD operation may, at leastcurrently, be more likely.

FIG. 5 is a signalling ladder diagram schematically representing modesof operation for one of the terminal devices (UEs) 406, 408 and the basestation (eNB) 404 schematically represented in FIG. 4 in accordance withcertain embodiments of the present disclosure. The operation is forcommunicating using a primary component carrier (associated with aprimary cell) operating on radio resources within a first frequency bandand a secondary component carrier (associated with a secondary cell)operating on radio resources within a second frequency band inaccordance with certain embodiments of the present disclosure. Asdiscussed above, the first frequency band is taken to correspond withresources that have been licensed for dedicated use by the operator ofthe wireless telecommunications system 400 whereas the second frequencyband is taken to correspond with resources that are shared by otherwireless communication technologies, and in particular in this exampleby Wi-Fi. In broad summary, some embodiments of the disclosure introducethe concept of establishing a plurality of transmission resourceconfigurations (e.g. frequencies) that might potentially be used for asecondary carrier in the context of carrier aggregation using radioresources that are shared between different network operators and/ordifferent wireless access technologies, and indicating to a terminaldevice which configuration is to be used in association with anallocation of transmission resources on the secondary carrier.

Some aspects of the operation represented in FIG. 5 are performed in agenerally iterative manner as discussed further below. Processing inaccordance with certain embodiments of the disclosure as schematicallyrepresented in FIG. 5 is shown starting from a stage at which theterminal device is configured for operation on the primary cellassociated with the primary carrier, but is not yet configured foroperation on the secondary cell associated with the secondary carrier.This may be, for example, because the terminal device has only justconnected to the primary cell or because a previous secondary cellconfiguration is no longer valid.

In step T1 the base station establishes a measure of radio usage in thesecond frequency band. In some example implementations the base stationmay itself measure radio usage at different frequencies across thesecond frequency band, but in this example it is assumed the terminaldevice makes these measurements and reports them to the base station.That is to say, in this example implementation the base stationestablishes radio usage across the second band (unlicensed band) fromreports received from the terminal device (and/or other terminal devicesoperating in the wireless telecommunications system).

Thus, the terminal device makes measurement of radio usage in the secondfrequency band in its environment. In particular, the terminal devicemeasures the degree of radio usage at different frequencies across thesecond frequency band. For example, the terminal device may use its WLANtransceiver module to scan for activity associated with other wirelesscommunication devices, for example, Wi-Fi access points. From this theterminal device may establish, for example, an indication of frequencyresources used by other wireless communications devices and/or anindication of a received signal strength for wireless communicationsassociated with other wireless communications devices and/or anindication of an identifier for the other wireless communications device(e.g. SSID). The terminal device may also scan for radio usage in thesecond frequency band by other devices operating according to otheroperating standards, for example Bluetooth and/or other LTE networks. Insome embodiments the terminal device might not separately measure radiousage by different technologies, but may simply measure an aggregatelevel of radio signals (which may include radio noise) in itsenvironment at different frequencies across the second frequency band.The terminal device then transmits an indication of the measurements ofradio usage at different frequencies across the second frequency band tothe base station. This may be done on uplink radio resources on thealready-configured primary cell to which the terminal device isconnected in accordance with conventional signalling techniques, forexample in accordance with the established principles of measurementreport RRC signalling. Based on the measurement information regardingradio usage in the second frequency band received from the terminaldevice, the base station establishes radio usage across the secondaryband in step T1 represented in FIG. 5.

In step T2 the base station determines a plurality of potentialtransmission resource configurations, e.g. a plurality of potentialcarrier frequencies and bandwidth, for a secondary component carrieroperating in the second frequency band. This determination is based onthe radio usage established in step T1. For example, the base stationmay be configured to determine four (or another number) of possiblefrequency configurations (e.g. in terms of centre frequency and/orbandwidth) for a secondary component carrier operating within the secondfrequency band. These may be selected to correspond with regions of thesecond frequency band determined to have the lowest amount of radiousage according to usage established in step T1. For example, if thesecond frequency band supports Wi-Fi and Bluetooth communications byother wireless communication devices operating in the radio environmentof the terminal device, the base station may identify regions of thesecond frequency band which are expected to suffer least frominterference from such communications. For example, regions of thesecond frequency band spectrum where the measurements of radio usageestablished in step T1 indicate there is relatively little radio trafficthat would interfere with LTE-based communications between the basestation and the terminal device. More generally, the base station maydetermine appropriate transmission resources (e.g. in terms of timeand/or frequency resources) from within the second frequency band todefine a plurality of potential configuration settings for a secondarycomponent carrier based on the radio usage determined in step T1 usingestablished techniques for selecting appropriate transmission resourcesin a competitive (opportunistic) radio environment when taking accountof measurements of existing usage. For example, the base station mayavoid transmission resources in regions of the second frequency band forwhich the terminal device measurement reports indicate a relatively highdegree of radio usage, and may instead preferentially selectconfigurations for the secondary carrier that make use of transmissionresources in spectral regions having a relatively low degree of radiousage. In this particular example it is assumed the base station isconfigured to select four potential configurations for a secondarycarrier corresponding to the configurations identified as having thelowest expectation of interference. In some cases account may also betaken of throughput. For example, a larger bandwidth that encompassessub-regions of the second frequency band having relatively high radiousage may nonetheless be selected over a smaller bandwidth that avoidsthe sub-regions associated with relatively high radio usage to avoidrestricting transmissions on the secondary carrier to a relativelynarrow bandwidths. In some cases the base station may also take intoaccount its own load, for example some carriers may already have beenassigned to other devices to operate using LTU-U.

For this particular example it is assumed step T2 results in thedetermination of four possible configuration settings, for example interms of carrier frequencies and/or carrier bandwidths, which mightsubsequently be used for secondary carrier operation. The differentsecondary carrier configuration settings may be contiguous ornon-contiguous across the second frequency band and may have the same ordifferent bandwidths. For example, the base station may determine thefollowing four potential configuration settings: Configuration 1=abandwidth of 5 MHz centred on a frequency of F₁; Configuration 2=abandwidth of 10 MHz centred on a frequency of F₂; Configuration 3=abandwidth of 10 MHz centred on a frequency of F₃, Configuration 4=abandwidth of 20 MHz centred on a frequency of F₄, where F₄=F₃+15 MHzsuch that Configuration 3 and 4 relate to contiguous frequencyresources. However, it will be appreciated this is simply one particularexample of what might be determined to be an appropriate group ofpotential configuration settings for a secondary carrier. In particular,in accordance with other implementations, there may be more or fewerpotential configuration settings determined in step T2, and furthermorethese configuration settings may be subject to restrictions according tothe implementation at hand. For example, if a particular implementationallows only a discrete number of bandwidths and/or frequencies for asecondary component carrier (e.g. according to a relevant operatingstandard for the wireless telecommunications system), this willcorrespondingly restrict the potential carrier configurations that mightbe determined in step T2.

Thus, a significant difference of the approach represented in FIG. 5 ascompared to previously proposed techniques for applying carrieraggregation in unlicensed spectrum is the determination of a pluralityof potential configuration settings for a secondary component carrieroperating in the unlicensed spectrum, as opposed to determining a singleconfiguration setting to be used for the secondary component carrieroperating in the unlicensed spectrum. That is to say, instead ofdetermining just the most appropriate (i.e. “best” configurationsetting), the top four configuration settings may be determined instead,for example. In this regard it will be appreciated there are variousdifferent ways of characterising the optimum/“best” configurationsettings according to the implementation at hand. For example, selectingconfigurations having relatively high bandwidth may be considered moreimportant in some situations that in some others. Likewise, selectingconfigurations having relatively low expected interference from existingradio usage may be considered more important in some situations than insome others. Overall, the specific manner in which specificconfigurations may be determined as potential configurations for thesecondary carrier is not of primary significance to the principlesunderlying embodiments of the disclosure.

In step T3 the base station provides the terminal device with anindication of the potential configuration settings. This may be done ondownlink radio resources on the already-configured primary cell inaccordance with conventional signalling techniques, for example inaccordance with the established principles of radio bearer(re)configuration message RRC signalling. However, whereas in accordancewith existing techniques the information would indicate theconfiguration of a single component carrier, the information transmittedin step T3 represents a plurality of potential transmission resourceconfiguration settings as established in step T2.

In step T4 the terminal device begins measuring channel quality for thesecondary carrier configured according to the different potentialconfigurations. The measurements of channel quality for the secondarycarrier may be based on established channel quality measurementtechniques in wireless telecommunications systems. In particular, themeasurements undertaken in step T4 may correspond with those undertakenfor conventional channel quality indicator (CQI) reporting in LTEwireless communication systems. The terminal device may sequentiallyconfigure its transceiver in accordance with the different potentialconfiguration settings received in step T3 and undertake channel qualitymeasurement for each secondary carrier configuration in turn based onconventional CQI reporting techniques.

In step T5 the terminal device communicates an indication of the channelquality measurements to the base station. Again, this may be done inaccordance with generally conventional CQI reporting techniques, exceptit is performed for each of the potential secondary carrierconfigurations.

It will be appreciated steps T4 and T5 are shown as separate steps inFIG. 5 for ease of representation. In practice it may be expected thatsteps T4 and T5 will be performed iteratively for each configurationsetting in turn as the terminal device hops through the potentialconfiguration settings. That is to say, the terminal device mayconfigure its transceiver in accordance with the first one of thepotential configuration settings, and then measure and report channelconditions for this configuration setting, and then reconfigure itstransceiver in accordance with a second one of the potentialconfiguration settings, and then measure and report channel conditionsfor this configuration setting, and so forth until channel qualityreports have been provided to the base station for a secondary carrieroperating in accordance with each of the potential configurationsettings. However, in another example implementation, and depending onthe terminal device's transceiver capabilities, the channel qualitymeasurement and reporting may be performed in parallel for multipleconfiguration settings.

Step T6 is performed when the base station is ready to schedule thetransmission of some data to the terminal device on the secondarycarrier. The nature of the data, and the reason why it needs to betransmitted, is not significant. Based on the channel quality reportsreceived in step T5, the base station selects one of the plurality ofpotential configuration settings for a secondary carrier to use fortransmitting the data to the terminal device. In this regard the basestation may, for example, choose the configuration setting which isassociated with the best channel conditions, as reported in step T5. Inaddition to selecting what is considered to be the most appropriateconfiguration setting for the secondary component carrier based on thechannel quality reports, the base station also selects resources withinthe secondary channel to use for communicating the data to the terminaldevice. These may be selected in accordance with generally conventionalscheduling techniques in wireless telecommunications systems, forexample against taking account of the channel quality reports for therelevant carrier configuration.

In step T7 the base station transmits a resource allocation message tothe terminal device indicating the resources within the secondarycarrier that are scheduled (allocated/granted) for use by the terminaldevice. The resource allocation message regarding the allocation ofresources within the secondary carrier may be based on conventionaltechniques, for example in an LTE context the message of step T7 may beprovided as downlink control information (DCI) signalling on (E)PDCCH inorder to indicate transmission resources on PDSCH according to generallyconventional techniques. Furthermore, the resource allocation messagerelating to the secondary carrier may be communicated on the primarycarrier in accordance with established cross-carrier schedulingtechniques in carrier aggregation scenarios. However, in accordance withembodiments of the present disclosure, the resource allocation messageindicating the allocation of resources within the secondary carrier isadditionally associated with an indication of the configuration settingselected by the base station in step T6 for configuring the secondarycarrier for transmitting the data to which the resource allocationmessage relates.

There are various ways in which the indication of the selectedconfiguration setting for the secondary carrier may be communicated tothe terminal device in association with the resource allocation message.In this particular example it is assumed the indication of the selectedconfiguration setting for the secondary carrier to be used for conveyingthe data on the resources indicated in the resource allocation messageis provided within the resource allocation message itself. This may beachieved, for example, by establishing a new format for downlink controlinformation which includes an indication of the selected one of theplurality of potential carrier configurations. For example, in animplementation in which there are four potential configuration settingsestablished for the secondary carrier, the downlink control informationassociated with the resource allocation message may include a two-bitindication as an index to which of the four potential configurationsettings is to be used. Other indications of the selected configurationincluded in the downlink control information may include, for example, apointer to an entry in a table of potential configuration settingsestablished according to an operating standard for the wirelesstelecommunications system, or a reference to a specific EARFCN(E-Absolute Radio Frequency Channel Number). In another exampleimplementation, a separate message may be defined for conveying theindication of the selected configuration setting to be used.Furthermore, the selected configuration setting may apply for only asingle subframe (i.e. for one resource allocation message) or may applyfor a plurality of subframes (i.e. for a plurality of resourceallocation messages). For example, the base station may convey theindication of the selected one of the potential carrier configurationsonce every frame and it may then be assumed to apply for each subframein the frame. In another implementation the base station may only conveyan indication of a selected one of the potential carrier configurationswhen it is changed. Thus the terminal device may be configured to assumea currently selected carrier configuration remains valid until itreceives an indication that a new configuration settings for thesecondary carrier has been selected for use by the base station.

In step T8 represented in FIG. 5, the base station proceeds tocommunicate data to the terminal device on a secondary component carrierconfigured in accordance with the selected configuration setting, andusing transmission resources within the secondary component carrier asidentified by the resource allocation message. The terminal device isable to configure its transceiver in accordance with the selectedconfiguration setting for the secondary carrier and decode the relevanttransmission resources to receive the data.

For implementations in which the indication of the selected carrierconfiguration is provided in the same subframe (time block) as the datato which the resource allocation message relates (for example within acontrol region of the subframe, e.g. within the (E)PDCCH resourceallocation message itself in an LTE-based implementation), the terminaldevices may receive and buffer radio signals on transmission resourcesassociated with all the potential carrier configurations so theappropriate transmission resources can be decoded once the selectedconfiguration setting is established by the terminal device from thesignalling received from the base station. In other implementations inwhich the indication of the selected carrier configuration is providedin advance of the subframe containing the data to which the resourceallocation message relates, the terminal device may configure itstransceiver for receiving the secondary carrier in accordance with theselected configuration settings to allow the allocated resources to bedecoded.

After the data is communicated in step T8, the processing may return tostep T4 and continue from there in an iterative manner.

Thus to summarise some aspects of the above-described embodiments of thedisclosure, a wireless telecommunications system is provided in which aplurality of potential configuration settings for a secondary carrieroperating in an unlicensed band are established and known to both theterminal device and the base station. The terminal device measureschannel conditions associated with each of the potential configurationsfor the secondary component carrier, and reports these to the basestation. Based on this the base station selects an appropriate one ofthe plurality of potential configurations to use for travelling data tothe terminal device. The base station may then transmit a resourceallocation message to the terminal device relating to the datatransmissions to be made on the secondary component carrier.Significantly, the base station also provides the terminal device withan indication of the secondary component carrier configuration settingto be used for receiving the data associated with the resourceallocation message. In accordance with certain embodiments of thedisclosure the indication of the selected configuration setting for thesecond component carrier (e.g. the time and/or frequency resources to beused for the second component carrier) is conveyed from the base stationusing layer 1 signalling/physical layer signalling. This allows forfaster switching between different carrier configuration settings thanwould be the case with conventional RRC reconfiguration signalling. Thisallows the base station to react relatively quickly to fluctuations ininterference from other radio access technologies operating within thesecond frequency band. In particular, this can be done on a persubframe/time block basis if desired. This would not be possible withprevious techniques in which a reconfiguration of settings for asecondary component carrier is established through RRC signalling. Aswell as being beneficial for the general operation of the wirelesstelecommunications system itself, the ability to rapidly switchconfiguration settings for the secondary carrier may also help reducethe extent to which communications between the base station and theterminal device interfere with other devices trying to access the sharedresources of the second frequency band. What is more, frequent changesin configuration setting for a secondary component carrier can be madein accordance with embodiments of the disclosure, for example inresponse to frequent changes in channel conditions within the secondfrequency band, with less signalling overhead than with existingtechniques.

As described above, in accordance with certain embodiments of theinvention, a plurality of potential transmission resourcesconfigurations may be determined from a scan of radio usage within thesecond frequency band by the terminal device, for example using a WLANtransceiver module and/or a Bluetooth transceiver module. Once theterminal device has performed this initial scan, the resulting potentialcarrier configuration settings may be maintained for an extended period,for example until the base station determines from the channel qualityreports received from the terminal device that none of the potentialconfiguration settings are able to provide a desired level ofperformance. This can result in a saving in terminal device batterypower since it does not need to measure and report on radio usage in thesecond frequency band each time a configuration setting for the secondcomponent carrier is to be changed. In the event the base stationdetermines from the channel quality reports received from the terminaldevice that none of the current plurality of potential configurationsettings are able to provide an acceptable degree of performance, thebase station may in effect return to step T1 of the processingrepresented in FIG. 5 to begin the process of establishing a newplurality of potential carrier configurations for the secondarycomponent carrier. This may involve the base station sending a requestmessage to the terminal device to trigger the terminal device to measureand report on radio usage across the second frequency band. This requestmay, for example, be made in accordance with conventional controlsignalling techniques on the primary carrier.

It will be appreciated the processing represented in FIG. 5 may bemodified for operation in accordance with other embodiments of thedisclosure. For example, whereas steps T4 and T5 as described above maybe performed by the terminal device cycling through the differentpotential transmission resources configurations, in accordance with someembodiments a terminal device might only make channel quality reports inrespect of a currently-selected configuration (i.e. in respect of theconfiguration indicated in step T7) in the processing of FIG. 5 inaccordance with conventional LTE procedures. In this case, the basestation may then request the terminal device to make measurements inrespect of the other potential configurations. That is to say, the basestation may send a request message to the terminal device, for exampleusing conventional request signalling techniques, to indicate theterminal device should measure channel quality for one or more otherpotential configurations, and provide the basis with a corresponding oneor more channel quality report. That is to say, the base station may beconfigured to control the manner in which the terminal device isperforming and we supporting channel quality/channel state measurements.

It will be appreciated that while the above-described embodiments arefocused on a single base station supporting both the primary componentcarrier the secondary component carrier, more generally these could betransmitted from separate base stations. In this regard, thenetwork-side processing in accordance with embodiments of the presentdisclosure may be performed by network infrastructure equipment whichcomprises, for example, one base station or more than one base station,and potentially other network infrastructure equipment elementsaccording to the operating principles of the wireless telecommunicationsnetwork in which the approach is implemented.

It will be appreciated the principles described above may be applied inrespect of a wireless telecommunications system supporting carrieraggregation with secondary component carriers operating in a frequencyband over which the wireless telecommunications system does not haveexclusive control irrespective of whether or not the wirelesstelecommunications system requires an administrative license to operatein the secondary frequency band. That is to say, it will be appreciatedthe terminology “unlicensed” is used herein for convenience to refer tooperation in a band over which the wireless telecommunications systemdoes not have exclusive access. In many implementations this willcorrespond with a licence exempt frequency band. However, in otherimplementations the operation may be applied in a frequency band whichis not unlicensed in the strict administrative sense, but which isnonetheless available for shared/opportunistic use by devices operatingaccording to different wireless access technologies (e.g. LTE-based,Wi-Fi-based and/or Bluetooth-based technologies) and/or multiplenetworks operating according to the same technology (e.g. LTE-basedwireless communication systems provided by different network operators).In this regard the terminology such as “unlicensed frequency band” maybe considered to refer generally to a frequency band in which resourcesare shared by different wireless communications systems. Accordingly,while the term “unlicensed” is commonly used to refer to these types offrequency bands, in some deployment scenarios an operator of a wirelesstelecommunications system may nonetheless be required to hold anadministrative license to operate in these frequency bands.

Thus there has been described a method of operating a terminal deviceand network infrastructure equipment in a wireless telecommunicationssystem for communicating on a primary cell supporting a primarycomponent carrier on radio resources within a first frequency band and asecondary cell supporting a secondary component carrier on radioresources within a second frequency band. The infrastructure equipmentestablishes a plurality of configuration settings for the secondarycarrier (e.g. in terms of frequency and/or time resources) based onmeasurements of radio usage in the second frequency band. Theconfiguration settings (which may in some respects be viewed assemi-static secondary cell pre-configurations) are conveyed to theterminal device. The terminal device makes channel quality measurementsfor the secondary component carrier according to the differentconfiguration settings and reports these to the infrastructureequipment. Based on these measurements of channel quality for thedifferent configurations of the secondary carrier, the infrastructureequipment selects one of the configuration settings, and conveys anindication of this to the terminal device in association with anallocation of transmission resources on the secondary component carrier.Data is then transmitted from the infrastructure equipment to theterminal device using the allocated resources on the secondary componentcarrier with the secondary component carrier operating in accordancewith the selected configuration.

Thus, communications between the terminal device and the networkinfrastructure may be made using a primary cell associated with aprimary component carrier configuration and a secondary cell associatedwith a plurality of potential secondary component carrier configurations(e.g. frequency characteristics). Transmissions of data from the networkinfrastructure to the terminal device may then be associated with anindication of which of the potential/candidate secondary componentcarriers are to be used for the data. The indication of the secondarycarrier may be conveyed using physical layer/layer 1 signalling, forexample on the primary cell. In particular, the indication of thesecondary carrier may be associated with a control message indicating anallocation of transmission resources on the secondary carrier forassociated data. The network infrastructure element responsible forselecting the secondary component carrier from the plurality ofpotential secondary carriers may do so based on channel conditionmeasurements, for example, using channel quality indicator (CQI) reportsreceived from the terminal device.

Further particular and preferred aspects of the present invention areset out in the accompanying independent and dependent claims. It will beappreciated that features of the dependent claims may be combined withfeatures of the independent claims in combinations other than thoseexplicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. As will be understood by thoseskilled in the art, the present invention may be embodied in otherspecific forms without departing from the spirit or essentialcharacteristics thereof. Accordingly, the disclosure of the presentinvention is intended to be illustrative, but not limiting of the scopeof the invention, as well as other claims. The disclosure, including anyreadily discernible variants of the teachings herein, define, in part,the scope of the foregoing claim terminology such that no inventivesubject matter is dedicated to the public.

Respective features of the present disclosure are defined by thefollowing numbered paragraphs:

Paragraph 1. A method of operating a terminal device in a wirelesstelecommunications system for communicating with network infrastructureequipment on a primary cell supporting a primary component carrier onradio resources within a first frequency band and a secondary cellsupporting a secondary component carrier on radio resources within asecond frequency band, wherein the method comprises: receiving from thenetwork infrastructure equipment an indication of a plurality ofpotential configuration settings for the secondary component carrier;receiving from the network infrastructure equipment an allocationmessage indicating an allocation of transmission resources to be usedfor communicating data between the network infrastructure equipment andthe terminal device on the secondary component carrier; receiving fromthe network infrastructure equipment in association with the allocationmessage an indication of a selected one of the plurality of potentialconfiguration settings for the secondary component carrier to be usedfor communicating the data; and receiving the data from the networkinfrastructure equipment using the allocated resources on the secondarycomponent carrier operating in accordance with the selected one of theplurality of potential configuration settings.

Paragraph 2. The method of paragraph 1, further comprising: receivingfrom the network infrastructure equipment a further allocation messageindicating a further allocation of transmission resources to be used forcommunicating further data between the network infrastructure equipmentand the terminal device on the secondary component carrier; receivingfrom the network infrastructure equipment in association with thefurther allocation message a further indication of another selected oneof the plurality of potential configuration settings for the secondarycomponent carrier to be used for communicating the further data; andreceiving the further data from the network infrastructure equipmentusing the further allocated resources on the secondary component carrieroperating in accordance with the other selected one of the plurality ofpotential configuration settings.

Paragraph 3. The method of paragraph 1 or 2, wherein the allocationmessage includes the indication of the selected one of the plurality ofpotential configuration settings for the secondary component carrier tobe used for communicating the data.

Paragraph 4. The method of any one of paragraphs 1 to 3, wherein theindication of the selected one of the plurality of potentialconfiguration settings for the secondary component carrier is specificto the associated allocation message.

Paragraph 5. The method of any one of paragraphs 1 to 4, wherein theindication of the selected one of the plurality of potentialconfiguration settings is associated with a plurality of allocationmessages indicating allocations of transmission resources to be used forcommunicating data between the network infrastructure equipment and theterminal device on the secondary component carrier.

Paragraph 6. The method of any one of paragraphs 1 to 5, wherein theindication of the selected one of the plurality of potentialconfiguration settings is received by the terminal device from thenetwork infrastructure equipment using layer 1 signalling.

Paragraph 7. The method of any one of paragraphs 1 to 6, whereincommunications between the network infrastructure equipment and theterminal device are made with a radio frame structure comprising aplurality of time blocks, and wherein the selected one of the pluralityof potential configuration settings for the secondary component carrieris valid for one time block or more time blocks.

Paragraph 8. The method of paragraph 7, wherein the indication of theselected one of the plurality of potential configuration settings isreceived in the same time block as the allocation message with which itis associated.

Paragraph 9. The method of paragraph 7, wherein the indication of theselected one of the plurality of potential configuration settings isreceived in a time block that is before a time block containing theallocation message with which it is associated.

Paragraph 10. The method of any one of paragraphs 1 to 9, wherein theallocation message and the indication of a selected one of the pluralityof potential configuration settings for the secondary component carrierare received using transmission resources in the first frequency band.

Paragraph 11. The method of any one of paragraphs 1 to 10, wherein theindication of a plurality of potential configuration settings for thesecondary component carrier are received using transmission resources inthe first frequency band.

Paragraph 12. The method of any one of paragraphs 1 to 11, wherein theindication of a plurality of potential configuration settings for thesecondary component carrier are received using radio resource control,RRC, signalling.

Paragraph 13. The method of any one of paragraphs 1 to 12, furthercomprising: performing channel quality measurements for differentconfigurations of the secondary component carrier corresponding with thepotential configuration settings for the secondary component carrier;and conveying an indication of the channel quality measurements to thenetwork infrastructure equipment.

Paragraph 14. The method of any one of paragraphs 1 to 13, wherein thesecond frequency band comprises radio resources which are shared withwireless communication devices that are not part of the wirelesstelecommunications system.

Paragraph 15. The method of any one of paragraphs 1 to 14, furthercomprising making measurements of radio usage in the second frequencyband and transmitting an indication of the measurements of radio usagein the second frequency band to the network infrastructure equipmentprior to receiving from the network infrastructure equipment theindication of a plurality of potential configuration settings for thesecondary component carrier.

Paragraph 16. The method of paragraph 15, wherein the indication of themeasurements of radio usage in the second frequency band are transmittedto the network infrastructure equipment using transmission resources inthe first frequency band.

Paragraph 17. The method of paragraph 15 or 16, wherein communicationsfrom the network infrastructure equipment are received by the terminaldevice with a receiver operating in accordance with a first wirelesscommunications operating standard and the measurements of radio usage inthe second frequency band are made with a receiver operating inaccordance with a second wireless communications operating standard thatis different from the first wireless communications operating standard.

Paragraph 18. The method of paragraph 17, wherein the first wirelesscommunications operating standard is a cellular telecommunicationsoperating standard and the second wireless communications operatingstandard is a non-cellular telecommunications operating standard.

Paragraph 19. The method of any one of paragraphs 15 to 18, wherein theindication of the measurements of radio usage in the second frequencyband are transmitted to the network infrastructure equipment using radioresource control, RRC, signalling.

Paragraph 20. The method of any one of paragraphs 1 to 19, wherein thepotential configuration settings for the secondary component carriercomprises indications of potential frequency and/or time resources to beused for the secondary component carrier.

Paragraph 21. A terminal device for use in a wireless telecommunicationssystem for communicating with network infrastructure equipment on aprimary cell supporting a primary component carrier on radio resourceswithin a first frequency band and a secondary cell supporting asecondary component carrier on radio resources within a second frequencyband, wherein the terminal device comprises a controller unit and atransceiver unit configured to operate together to: receive from thenetwork infrastructure equipment an indication of a plurality ofpotential configuration settings for the secondary component carrier;receive from the network infrastructure equipment an allocation messageindicating an allocation of transmission resources to be used forcommunicating data between the network infrastructure equipment and theterminal device on the secondary component carrier; receive from thenetwork infrastructure equipment in association with the allocationmessage an indication of a selected one of the plurality of potentialconfiguration settings for the secondary component carrier to be usedfor communicating the data; and receive the data from the networkinfrastructure equipment using the allocated resources on the secondarycomponent carrier operating in accordance with the selected one of theplurality of potential configuration settings.

Paragraph 22. Circuitry for a terminal device for use in a wirelesstelecommunications system for communicating with network infrastructureequipment on a primary cell supporting a primary component carrier onradio resources within a first frequency band and a secondary cellsupporting a secondary component carrier on radio resources within asecond frequency band, wherein the circuitry comprises a controllerelement and a transceiver element configured to operate together to:receive from the network infrastructure equipment an indication of aplurality of potential configuration settings for the secondarycomponent carrier; receive from the network infrastructure equipment anallocation message indicating an allocation of transmission resources tobe used for communicating data between the network infrastructureequipment and the terminal device on the secondary component carrier;receive from the network infrastructure equipment in association withthe allocation message an indication of a selected one of the pluralityof potential configuration settings for the secondary component carrierto be used for communicating the data; and receive the data from thenetwork infrastructure equipment using the allocated resources on thesecondary component carrier operating in accordance with the selectedone of the plurality of potential configuration settings.

Paragraph 23. A method of operating network infrastructure equipment ina wireless telecommunications system for communicating with a terminaldevice on a primary cell supporting a primary component carrier on radioresources within a first frequency band and a secondary cell supportinga secondary component carrier on radio resources within a secondfrequency band, wherein the method comprises: transmitting to theterminal device an indication of a plurality of potential configurationsettings for the secondary component carrier; transmitting to theterminal device an allocation message indicating an allocation oftransmission resources to be used by for communicating data to theterminal device on the secondary component carrier; transmitting to theterminal device in association with the allocation message an indicationof a selected one of the plurality of potential configuration settingsfor the secondary component carrier to be used for communicating thedata; and transmitting the data to the terminal device using theallocated resources on the secondary component carrier operating inaccordance with the selected one of the plurality of potentialconfiguration settings.

Paragraph 24. The method of paragraph 23, further comprising obtainingan indication of radio usage in the second frequency band andestablishing the plurality of potential configuration settings for thesecondary component carrier based on the indication of radio usage inthe second frequency band.

Paragraph 25. The method of paragraph 24, wherein the indication ofradio usage in the second frequency band is obtained from measurementsof radio usage in the second frequency band made by the networkinfrastructure equipment and/or measurements of radio usage in thesecond frequency band made by the terminal device and reported tonetwork infrastructure equipment and/or measurements of radio usage inthe second frequency band made by other terminal devices operating inthe wireless telecommunications system and reported to networkinfrastructure equipment.

Paragraph 26. The method of any one of paragraphs 23 to 25, furthercomprising receiving from the terminal device an indication ofmeasurements of channel quality made by the terminal device fordifferent configurations of the secondary component carriercorresponding with the potential configuration settings for thesecondary component carrier, and determining the selected one of theplurality of potential configuration settings for the secondarycomponent carrier to be used for communicating the data based on theindication of measurements of channel quality for the differentconfigurations of the secondary component carrier.

Paragraph 27. Network infrastructure equipment for use in a wirelesstelecommunications system for communicating with a terminal device on aprimary cell supporting a primary component carrier on radio resourceswithin a first frequency band and a secondary cell supporting asecondary component carrier on radio resources within a second frequencyband, wherein the network infrastructure equipment comprises acontroller unit and a transceiver unit configured to operate togetherto: transmit to the terminal device an indication of a plurality ofpotential configuration settings for the secondary component carrier;transmit to the terminal device an allocation message indicating anallocation of transmission resources to be used by for communicatingdata to the terminal device on the secondary component carrier; transmitto the terminal device in association with the allocation message anindication of a selected one of the plurality of potential configurationsettings for the secondary component carrier to be used forcommunicating the data; and transmit the data to the terminal deviceusing the allocated resources on the secondary component carrieroperating in accordance with the selected one of the plurality ofpotential configuration settings.

Paragraph 28. Circuitry for network infrastructure equipment for use ina wireless telecommunications system for communicating with a terminaldevice on a primary cell supporting a primary component carrier on radioresources within a first frequency band and a secondary cell supportinga secondary component carrier on radio resources within a secondfrequency band, wherein the circuitry comprises a controller element anda transceiver element configured to operate together to: transmit to theterminal device an indication of a plurality of potential configurationsettings for the secondary component carrier; transmit to the terminaldevice an allocation message indicating an allocation of transmissionresources to be used by for communicating data to the terminal device onthe secondary component carrier; transmit to the terminal device inassociation with the allocation message an indication of a selected oneof the plurality of potential configuration settings for the secondarycomponent carrier to be used for communicating the data; and transmitthe data to the terminal device using the allocated resources on thesecondary component carrier operating in accordance with the selectedone of the plurality of potential configuration settings.

REFERENCES

-   [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based    radio access”, John Wiley and Sons, 2009-   [2] ETSI TS 136 211 V11.5.0 (2014-01)/3GPP TS 36.211 version 11.5.0    Release 11-   [3] ETSI TS 136 212 V11.4.0 (2014-01)/3GPP TS 36.212 version 11.4.0    Release 11-   [4] ETSI TS 136 213 V11.6.0 (2014-03)/3GPP TS 36.213 version 11.6.0    Release 11-   [5] ETSI TS 136 321 V11.5.0 (2014-03)/3GPP TS 36.321 version 11.5.0    Release 11-   [6] ETSI TS 136 331 V11.7.0 (2014-03)/3GPP TS 36.331 version 11.7.0    Release 11

What is claimed is:
 1. A terminal device configured to operate in awireless telecommunications system and for communicating on a primarycell supporting a primary component carrier on radio resources within afirst, licensed frequency band and a secondary cell supporting asecondary component carrier on radio resources within a second,unlicensed frequency band, the terminal device comprising: circuitryconfigured to receive an allocation message indicating an allocation oftransmission resources to be used for receiving data at the terminaldevice on the secondary component carrier; receive, in association withthe allocation message, an indication of a selected one of a pluralityof configuration settings for the secondary component carrier to be usedfor receiving the data, wherein the indication comprises a pointer to anentry in a table of potential configuration settings establishedaccording to an operating standard for the wireless telecommunicationssystem; and receive the data using the allocated resources on thesecondary component carrier operating in accordance with the selectedone of the plurality of configuration settings, wherein communicationsbetween the wireless telecommunications system and the terminal deviceare made with a radio frame structure comprising a plurality ofsubframes, and the selected one of the plurality of configurationsettings for the secondary component carrier is valid for one or moresubframes.
 2. The terminal device of claim 1, wherein the circuitry isconfigured to: receive a further allocation message indicating a furtherallocation of transmission resources to be used for receiving furtherdata at the terminal device on the secondary component carrier; receive,in association with the further allocation message, a further indicationof another selected one of the plurality of configuration settings forthe secondary component carrier to be used for receiving the furtherdata; and receive the further data using the further allocated resourceson the secondary component carrier operating in accordance with theother selected one of the plurality of configuration settings.
 3. Theterminal device of claim 1, wherein the allocation message includes theindication of the selected one of the plurality of configurationsettings for the secondary component carrier to be used forcommunicating the data.
 4. The terminal device of claim 1, wherein theindication of the selected one of the plurality of configurationsettings for the secondary component carrier is specific to theassociated allocation message.
 5. The terminal device of claim 1,wherein the indication of the selected one of the plurality ofconfiguration settings is associated with a plurality of allocationmessages indicating allocations of transmission resources to be used forreceiving data at the terminal device on the secondary componentcarrier.
 6. The terminal device of claim 1, wherein the indication ofthe selected one of the plurality of configuration settings is receivedby the terminal device from the wireless telecommunications system usinglayer 1 signaling.
 7. The terminal device of claim 1, wherein theindication of the selected one of the plurality of configurationsettings is received in the same subframe as the allocation message withwhich it is associated.
 8. The terminal device of claim 1, wherein theindication of the selected one of the plurality of configurationsettings is received in a subframe that is before a subframe containingthe allocation message with which it is associated.
 9. The terminaldevice of claim 1, wherein the allocation message and the indication ofa selected one of the plurality of configuration settings for thesecondary component carrier are received using transmission resources inthe first, licensed frequency band.
 10. The terminal device of claim 1,wherein an indication of a plurality of configuration settings for thesecondary component carrier are received using transmission resources inthe first, licensed frequency band.
 11. The terminal device of claim 1,wherein an indication of a plurality of configuration settings for thesecondary component carrier are received using radio resource control(RRC) signaling.
 12. The terminal device of claim 1, wherein thecircuitry is configured to: perform channel quality measurements for thesecondary component carrier; and convey an indication of the channelquality measurements to the wireless telecommunications system.
 13. Theterminal device of claim 1, wherein the second, unlicensed frequencyband comprises radio resources which are shared with wirelesscommunication devices that are not part of the wirelesstelecommunications system.
 14. The terminal device of claim 1, whereinthe circuitry is configured to: make measurements of radio usage in thesecond, unlicensed frequency band and transmit an indication of themeasurements of radio usage in the second, unlicensed frequency band tothe wireless telecommunications system prior to receiving the indicationof the selected one of the plurality of configuration settings for thesecondary component carrier.
 15. The terminal device of claim 14,wherein the indication of the measurements of radio usage in the second,unlicensed frequency band are transmitted using transmission resourcesin the first, licensed frequency band.
 16. The terminal device of claim14, wherein communications from the wireless telecommunication systemare received by the terminal device operating in accordance with a firstwireless communications standard and the measurements of radio usage inthe second frequency band are made by the terminals device operating inaccordance with a second wireless communications standard that isdifferent from the first wireless communications standard.
 17. Theterminal device of claim 16, wherein the first wireless communicationsstandard is a cellular telecommunications standard and the secondwireless communications standard is a non-cellular telecommunicationsstandard.
 18. The terminal device of claim 14, wherein the indication ofthe measurements of radio usage in the second, unlicensed frequency bandare transmitted using radio resource control (RRC) signaling.
 19. Theterminal device of claim 1, wherein the indication of the selected oneof the plurality of configuration settings for the secondary componentcarrier comprises an indication of time resources to be used for thesecondary component carrier.
 20. A terminal device for use in a wirelesstelecommunications system for communicating on a primary cell supportinga primary component carrier on radio resources within a first, licensedfrequency band and a secondary cell supporting a secondary componentcarrier on radio resources within a second, unlicensed frequency band,the terminal device comprising: a controller and a transceiverconfigured to operate together to: receive an allocation messageindicating an allocation of transmission resources to be used forreceiving data at the terminal device on the secondary componentcarrier; receive, in association with the allocation message, anindication of a selected one of a plurality of configuration settingsfor the secondary component carrier to be used for receiving the data,wherein the indication comprises a pointer to an entry in a table ofpotential configuration settings established according to an operatingstandard for the wireless telecommunications system; and receive thedata using the allocated resources on the secondary component carrieroperating in accordance with the selected one of the plurality ofconfiguration settings, wherein communications between the wirelesstelecommunications system and the terminal device are made with a radioframe structure comprising a plurality of subframes, and the selectedone of the plurality of configuration settings for the secondarycomponent carrier is valid for one or more subframes.
 21. A method ofoperating a terminal device in a wireless telecommunications system forcommunicating on a primary cell supporting a primary component carrieron radio resources within a first, licensed frequency band and asecondary cell supporting a secondary component carrier on radioresources within a second, unlicensed frequency band, the methodcomprising: receiving an allocation message indicating an allocation oftransmission resources to be used for receiving data at the terminaldevice on the secondary component carrier; receiving, in associationwith the allocation message, an indication of a selected one of aplurality of configuration settings for the secondary component carrierto be used for receiving the data, wherein the indication comprises apointer to an entry in a table of potential configuration settingsestablished according to an operating standard for the wirelesstelecommunications system; and receiving the data using the allocatedresources on the secondary component carrier operating in accordancewith the selected one of the plurality of configuration settings,wherein communications between the wireless telecommunications systemand the terminal device are made with a radio frame structure comprisinga plurality of subframes, and the selected one of the plurality ofconfiguration settings for the secondary component carrier is valid forone or more subframes.